Valve arrangement for well pumps



Dec. 28, 1965 w. L. BRIGMAN 3,225,696

VALVE ARRANGEMENT FOR WELL PUMPS Filed Feb. 8, 1965 INVENTOR. WALTER L. BmGMAN ATTORNEYS United States Patent 3,225,696 VALVE ARRANGEMENT FOR WELL PUMPS Walter L. Brigman, 307 Eleby Road, Rockingham, N.C. Filed Feb. 8, 1965, Ser. No. 431,073 5 Claims. (Cl. 103-6) This invention pertains to a valve arrangement for well pumps, and more particularly to a control valve apparatus for use with a centrifugal ejector pump for improving the operation of the water supply system using such a pump.

-In areas Where a central water supply system is not available as a source of water, reliance for water supply is commonly placed on a well. In order to obtain water pressure in a well supply system, water must either be pumped into a storage tank positioned some distance above the point of use or an air cushion tank must be used. An air cushion tank, as generally well known, is a water supply tank in which a cushion of air is trapped above the water contained in the tank. As the air is compressible, water may be pumped into the tank under pressure to compress the air cushion and the pressure thus developed by compressing the air cushion becomes available to pressurize the water supply system. In such a system, the pressure within the tank fluctuates as water is removed from the tank and this fluctuation is used to control the operation of the system pump.

One well-known type of pump used with air cushion pressure tank water supply systems is referred to as a centrifugal ejector pump. Such pumps use two stages, arranged for series flow. One stage is an ejector pump, which is a pump operating on the theory of the entrainment of fluid by a high velocity jet directed through a venturi tube, and also known as a jet pump. The second stage of the centrifugal ejector pump is a centrifugal pump, receiving as an input the output from the ejector pump and supplying Water under pressure to the water system which includes an air cushion water pressure tank. Centrifugal ejector pumps for such use are well known and are shown, as an example, in Conery Patent No. 2,524,770. As indicated in that patent, centrifugal ejector pumps are adaptable for use either with shallow Wells or with deep wells. In a shallow well application, the ejector stage of the centrifugal ejector pump is posi tioned immediately adjacent the centrifugal stage. In a deep well application, the ejector stage of the pump is placed down within the well.

Water supply system using centrifugal ejector pumps and an air cushion water pressure tank are subject to various difliculties. First, it is well known that air is soluble in water. For this reason, the air cushion trapped above the water in an air cushion pressure tank, in order to provide pressure for the water supply system, is gradually absorbed into the water in the tank. If the air cushion is not replenished from time to time, the tank becomes increasingly filled with water and the size of the air cushion is constantly reduced. Eventually, the tank will become entirely filled with water only, or Water-logged, and is no longer effective to provide pressurization for the water supply system. When this occurs, the pressure control which is normally used to operate the pump in response to a decrease in pressure within the tank resulting from the removal of water from the pressure tank causes the pump to operate at any time the water is drawn from the supply system, as the pump then provides the only means for pressurizing the supply system, and this more frequent operation substantially increases pump wear.

A second failing of water supply systems using centrifugal ejector pumps and an air cushion water pressure tank 0 "ice results from certain characteristics of the pump and tank system. In the operation of centrifugal ejector pumps, the output of water from the centrifugal stage depends upon the pressure differential across the pump rotor or head pressure. Once a certain predetermined output pressure from the centrifugal stage has been reached, the recirculation of flow to and through the ejector stage hecomes effective to create and thereafter maintain a predetermined pressure condition at the input side of the centrifugal rotor. Subsequently, as more water is pumped into the air cushion pressure tank and higher pressures are developed within that tank by the compression of the air cushion, the centrifugal stage must pump against a higher head pressure. This higher head pressure reduces the quantity of water flow through the pump, which in turn extends the pumping time required to deliver the necessary quantity of water into the tank. Frequently, such extended pumping cycles contribute to excessive pump wear.

The valve arrangement and apparatus of this invention provides a solution for these two problems encountered in water supply systems using a centrifugal ejector pump and an air cushion water pressure tank, by providing that the air cushion within the pressure tank is maintained and the pumping time for the pump is reduced. Broadly, this solution is obtained by balancing pressures across the centrifugal stage of the pump and admitting flow of air to the input side of the centrifugal stage to be carried by water flow into the tank to maintain the air cushion.

It is an object of this invention to provide an improved arrangement for reducing pump running load in a water supply system using a centrifugal ejector pump and an air cushion water pressure tank.

A further object of this invention is to provide an improved valve arrangement and apparatus effective to both maintain an air cushion within an air cushion water pressure tank and reduce the pump running load in a water supply system using a centrifugal ejector pump and an air cushion water pressure tank.

Some of the objects of the invention having been stated, other objects will appear as the description proceeds, when taken in connection with the accompanying drawings, in which:

FIGURE 1 is a perspective view, in partial section, of a portion of a Water supply system incorporating the present invention;

FIGURE 2 is a side view, in partial section, of the valve arrangement and apparatus of this invention;

FIGURE 3 is a detailed sectional view of a portion of the valve arrangement and apparatus shown in FIG- URE 2;

FIGURE 4 is a schematic illustration of the application of the valve arrangement and apparatus of this invention to the water supply system of FIGURE 1.

Briefly, the valve arrangement and apparatus of this invention uses a hollow housing connected by a conduit to the input side of the centrifugal stage of a centrifugal ejector pump. Thus, the pressure at the input side of the centrifugal stage is applied to or available at the interior of the housing. The hollow housing receives two valve assemblies, each communicating with the interior of the housing. One valve assembly operatively communicates with the atmosphere, while the other valve assembly operatively communicates with the interior of the air cushion water pressure tank, below the normal level of the air cushion at the pump cut-off pressure. Both valve assemblies. operate in response to a predetermined pressure differential across the valve to admit either air or water to the input side of the centrifugal stage of the pump, depending upon the particular pressure condition existing at the input side of the pump. On pump start-up, when a vacuum condition exists at the input side of the centrifugal stage, the valve assembly which is operatively com- Inunicating with the atmosphere opens to admit a flow of air into the input side of the centrifugal stage, to be carried with water flow through the stage and into the air cushion water pressure tank, to replenish and maintain the air cushion. During pump operation, the second valve assembly which is in operative communication with water Within the air cushion water pressure tank opens to admit a flow of water to the input side of the centrifugal stage, thus balancing the pressures across the centrifugal stage, and making possible a significant reduction in effective head pressure when the pump is completing a cycle.

A more detailed understanding of the valve arrangement and apparatus of this invention may be gained from a description taken in conjunction with the drawing. In FIGURE 1 there is shown a shallow well water supply system to which the valve arrangement and apparatus of this invention is applied, using structure basically similar to that taught in the Conery patent mentioned above. A centrifugal ejector pump is used, which has an electrical motor 11 driving the centrifugal impeller of the pump and a pressure control 12 operating the pump in response to pressure fluctuations within an air cushion water pressure tank 13. The centrifugal ejector pump 10 has an input connection to a well pipe 14, extending downwards in a well, and having a foot valve 15 with a wire screen guard. While the centrifugal ejector pump 10 is shown as arranged for shallow well pumping, it is entirely within the skill of persons familiar with the Con ery pump mentioned above to modify that pump for operation in a deep well system.

In order to provide for replenishment of the air cushion within the air pressure tank 13, and to reduce pump running load, I provide a valve arrangement and apparatus, indicated generally at 16, which is mounted on the pressure tank 13 and connected to the centrifugal ejector pump 10. As shown in section in FIGURE 2, the apparatus of this invention has a hollow housing 17 and a conduit 20 connecting the interior of the housing 17 with the centrifugal ejector pump 10. The hollow housing 17 receives two valve assemblies 21, 22. One valve assembly 21 operatively communicates with the atmosphere and with the interior of the housing, while a second valve assembly 22 is in operative communication with the interior of the pressure tank 13 and the interior of the housing 17. For purposes to be made more clear subsequently, the second valve assembly 22 communicates with the pressure tank 13 at a point below the air cushion, when the pressure within the tank 13 is at an intermediate level during a cycle, for example about 30 pounds pressure.

The particular construction of each valve assembly 21, 22 can be more completely understood for the sectional view of FIGURE 3. As shown there, each valve assembly includes a valve jacket 23 having a bore therethrough and a valve core received within the bore of the jacket 23. The valve core includes a valve body 24, which is received within the jacket 23 in threaded engagement and may be variably positioned within the jacket 23. The valve body 24 has an opening through the body, and defines at its inward end a valve seat 25. A valve member 26 is positioned immediately adjacent the valve seat 25, and normally may engage the valve seat 25 to prevent the passage of fluid through the valve assembly. The valve member 26 is resiliently urged against a valve seat 25 by a spring means 27, which includes a compression spring 30 and a clip 31. The various elements of the valve body are held in assembled relation by a valve rod 32, which is received by the valve body 24, fixed to the valve member 26, and extends through the spring 30 and clip 31. The bore through the valve jacket 23 is provided with an abutment 4 33 at the inward end, or the end of the bore remote from the position of the valve body 24.

In the complete valve assembly, a valve core is threaded into a jacket 23 until the clip 31 engages the abutment 33 within the jacket bore. Positioning the valve body 24 further inwardly of the jacket 23 compresses the spring 30 between the clip 31 and valve member 26, to resiliently urge the valve member against the valve seat 25. The relative position of the valve body 24 within the jacket 23 determines the force with which the valve member 26 is urged against the valve seat 25. Further, as the valve assembly opens to permit the flow of fluid in response to a pressure differential across the assembly sufficient to overcome the force with which the valve member 26 is urged against the seat 25 and move the member from the seat, the position of the valve body 24 also determines the predetermined pressure differential at which the particular valve assembly is operative.

The operation of the valve arrangement and apparatus of this invention will be most clearly understood when discussed in conjunction with the schematic showing of FIGURE 4, which illustrates the two stages of the centrifugal ejector pump and the other elements of a water supply system incorporating this invention. As there shown, the conduit 20 of the apparatus 16 is connected to the centrifugal ejector pump 10 at the input side of the centrifugal stage, intermediate the ejector stage and the centrifugal stage. The input to the ejector stage is drawn from the well pipe 14, and the output from the centrifugal stage is supplied to the pressure tank 13. An output line 34 from the pressure tank 13 leads to the remainder of the water supply system (not shown) and various points of use for the water. In order to further an understanding of the operation of this invention, some understanding of the operating characteristics of a centrifugal ejector pump is desirable before the operation of the valve arrangement and apparatus of this invention is described in detail.

As may be understood from the fact that the high pressure jet use-d in the ejector stage of the pump is derived from the centrifugal stage, the ejector stage of the pump is not effective to draw water from the well until a certain output pressure is developed by the centrifugal stage of the pump. Until the ejector stage becomes effective, the centrifugal stage operates, in effect, by itself and, as is characteristic of centrifugal pumps, develops a vacuum condition at the input side of the centrifugal stage. Typically, the ejector stage of the centrifugal ejector pump becomes sufficiently efiicient to overcome this vacuum condition when the output pressure from the centrifugal stage reaches approximately 23 to 25 pounds pressure. Then, as the pressure tank 13 is filled by the pump with both stages operating, a pressure condition exists at the input side of the centrifugal stage. Typically, the pressure control 12 permits the pump to run until the compression of the air cushion within the tank 13 is such to provide air pressure, applied to the water within the tank, of approximately 40 to 45 pounds, and the pump is then cut off. On removal of sufiicient Water from the pressure tank 13 to permit the air cushion to expand and drop the pressure Within the tank to approximately 20 pounds, the pump is again started and the cycle repeated.

When the valve arrangement and apparatus of this invention is applied to a water supply system substantially as described above in connection with FIGURE 4, the valve means 21 operatively communicating with the atmosphere is adjusted to be responsive to a predetermined vacuum condition at the input side of the centrifugal stage of the pump which exists at initial start up of the pump when the output pressure from the centrifugal stage is around 20 pounds pressure. At start up, the first valve means 21 opens in response to the pressure diiferential across the valve to admit air into the hollow housing 17, which air passes through the conduit 20 to the input side of the centrifugal stage of the pump 10. The air is carried through the pump with water flow and into the pressure tank 13. This carry-over of air through the pump replenishes the cushion within the pressure tank 13, thus maintaining the air cushion against the continuous absorption of air into the water in the tank, and avoids a water-logged tank. The first valve means 21 is adjusted, as outlined above, to close and stop the admission of air to the input side of the centrifugal stage once the output pressure from the centrifugal stage has risen beyond 20 pounds pressure. In a practical application, operation in this manner was found to effectively avoid a water-logged tank while not admitting an excessive quantity of air so as to substantially reduce the water capacity of the pressure tank 13. However, the cut-off point of the first valve means 21 may be varied when necessary.

While the pump is running and as the pressure within the tank 13 increases to about 32 pounds, the head pressure against which the centrifugal stage must operate increases, and the quantity of gallons per minute delivered by the pump drops accordingly. Absent the apparatus and valve arrangement of this invention, this decrease in flow would continue, with the pump delivering water at a steadily decreasing rate until the pump cut-off pressure of about 45 pounds is reached.

However, in accordance with this invention the water bypass valve assembly 22 opens at a tank pressure of about 32 pounds, to recirculate a small flow of water through the centrifugal stage and provide a more nearly balanced condition of pressures at the input and output side of that stage. Effectively, this more nearly balanced condition substantially lowers the head pressure against which the pump must work, and permits delivery of water at a higher rate of flow as the tank is filled to the established cut-01f pressure. This higher rate of flow delivery reduces the pump cycle time, and thus reduces wear on the pump.

In the drawings and specifications there has been set forth a preferred embodiment of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being defined in the claims.

I claim: 1. In combination with a water supply system having a pump with an ejector stage and a centrifugal stage operable in series and an air cushion pressure Water tank for receiving Water from the pump and supplying water under pressure to the system; means for maintaining the cushion within the water tank and reducing pump running load comprising:

first valve means operatively communicating with the atmosphere and the input side of the centrifugal stage of the pump and responsive to a predetermined pressure differential across the valve means for admitting air into the centrifugal stage to be carried by water flow into the tank to maintain the air cushion, and

second valve means operatively communicating with the water tank below the air cushion and the input side of the centrifugal stage of the pump and responsive to a predetermined pressure differential across the second valve means for admitting water from the tank to the centrifugal stage to balance the pressures across the centrifugal stage.

2. The combination claimed in claim 1 further comprising:

common conduit means operatively communicating with both valve means and with the pump intermediate the stages for providing the operative communication of the valve means and the input side of the centrifugal stage of the pump.

3. In combination with a water supply system having a pump with an ejector stage and a centrifugal stage operable in series and an air cushion pressure water tank for receiving water from the pump and supplying water under pressure to the system, means for maintaining the 6 cushion within the water tank and reducing pump running load comprising:

a hollow housing operatively connected to the water tank,

a conduit connecting the housing and the input side of the centrifugal stage of the pump,

first valve means carried by the housing and communicating with the atmosphere and the interior of the housing for admitting air into the centrifugal stage in response to a predetermined pressure condition at the input side of the centrifugal stage, whereby the air is carried by water flow into the tank to maintain the cushion, and

second valve means carried by the housing and communicating with the water tank below the cushion and the interior of the housing for admitting water from the tank to the centrifugal stage in response to a predetermined pressure condition at the input side of the centrifugal stage, whereby the water pressures across the pump are balanced.

4. The combination claimed in claim 3 in which each valve means comprises:

a valve jacket adapted to be received by said housing and having a bore through the jacket and a shoulder within the bore spaced from one end of the jacket, and

valve core means adjustably positioned within the jacket bore and abutting the shoulder and being openable in response to a pressure differential thereacross determined by the position of the core means within the bore.

5. In combination with a water supply system having a pump with an ejector stage and a centrifugal stage operable in series and an air cushion pressure water tank for receiving water from the pump and supplying water under ressure to the system; means for maintaining the cushion within the water tank and reducing pump running load comprising:

a hollow housing connected to the water tank below the cushion,

a conduit connecting the housing and the input side of the centrifugal stage of the pump,

a first valve jacket received by the housing and having a bore through the jacket and a shoulder within the the bore spaced from one end of the jacket,

a valve body adjustably positioned within the first jacket and having an opening through the body communicating with the atmosphere and the interior of the housing and having a valve seat,

a valve member carried by the valve body and engaging the valve seat,

spring means engaging the valve member and abutting the shoulder within the jacket for urging the valve member against the valve seat with a force determined by the position of the valve body within the first jacket,

the spring means force being overcome by a predetermined pressure differential across the valve member to displace the valve member from the valve seat and admit air to the input side of the centrifugal stage to be carried by water flow into the tank to maintain the air cushion,

a second valve jacket received by the housing and having a bore through the jacket and a shoulder within the bore spaced from one end of the jacket,

a second valve body adjustably positioned within the second jacket and having an opening through the the body communicating with the water tank below the air cushion and the first valve body through the interior of the housing and having a valve seat,

a second valve member carried by the second valve body and engaging the valve seat, and

spring means engaging the second valve member and abutting the shoulder within the second jacket for urging the valve member against the valve seat with a 3,225,696 7 8 force determined by the position of the valve body References Cited by the Examiner Within the second jacket, UNITED STATES PATENTS the spring means force being overcome by a predetermined pressure diifei'ential across the second valve 2,520,794 8/1950 Brady 1036 member to displace the valve member frqm the valve 5 2,524,770 0/1950 Conery 1036 seat and admit Water to the input side of the centrifu- ,171,351 3/ 1965 Shetler 1036 gal stage to balance the pressures across the centrifugal stage. DONLEY I. STOCKING, Primary Examiner. 

1. IN COMBINATION WITH A WATER SUPPLY SYSTEM HAVING A PUMP WITH AN EJECTOR STAGE AND A CENTRIFUGAL STAGE OPERABLE IN SERIES AND AN AIR CUSHION PRESSURE WATER TANK FOR RECEIVING WATER FROM THE PUMP AND SUPPLYING WATER UNDER PRESSURE TO THE SYSTEM; MEANS FOR MAINTAINING THE CUSHION WITHIN THE WATER TANK AND REDUCING PUMP RUNNING LOAD COMPRISING: FIRST VALVE MEANS OPERATIVELY COMMUNICATING WITH THE ATMOSPHERE AND THE INPUT SIDE OF THE CENTRIFUGAL STAGE OF THE PUMP AND RESPONSIVE TO A PREDETERMINED PRESSURE DIFFERENTIAL ACROS THE VALVE MEANS FOR ADMITTING AIR INTO THE CENTRIFUGAL STAGE TO BE CARRIED BY WATER FLOW INTO THE TANK TO MAINTAIN THE AIR CUSHION, AND SECOND VALVE MEANS OPERATIVELY COMMUNICATING WITH THE WATER TANK BELOW THE AIR CUSHION AND THE INPUT SIDE OF THE CENTRIFUGAL STAGE OF THE PUMP AND RESPONSIVE TO A PREDETERMINED PRESSURE DIFFERENTIAL ACROSS THE SCOND VALVE MEANS FOR ADMITTING WATER FROM THE TANK TO THE CENTRIFUGAL STAGE TO BALANCE THE PRESSURES ACROSS THE CENTRIFUGAL STAGE. 